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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>
Cc: Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Minchan Kim <minchan@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 32/34] mm: vmstat: account per-zone stalls and pages skipped during reclaim
Date: Fri,  8 Jul 2016 10:35:08 +0100
Message-ID: <1467970510-21195-33-git-send-email-mgorman@techsingularity.net> (raw)
In-Reply-To: <1467970510-21195-1-git-send-email-mgorman@techsingularity.net>

The vmstat allocstall was fairly useful in the general sense but
node-based LRUs change that.  It's important to know if a stall was for an
address-limited allocation request as this will require skipping pages
from other zones.  This patch adds pgstall_* counters to replace
allocstall.  The sum of the counters will equal the old allocstall so it
can be trivially recalculated.  A high number of address-limited
allocation requests may result in a lot of useless LRU scanning for
suitable pages.

As address-limited allocations require pages to be skipped, it's important
to know how much useless LRU scanning took place so this patch adds
pgskip* counters.  This yields the following model

1. The number of address-space limited stalls can be accounted for (pgstall)
2. The amount of useless work required to reclaim the data is accounted (pgskip)
3. The total number of scans is available from pgscan_kswapd and pgscan_direct
   so from that the ratio of useful to useless scans can be calculated.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
 include/linux/vm_event_item.h |  4 +++-
 mm/vmscan.c                   | 15 +++++++++++++--
 mm/vmstat.c                   |  3 ++-
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 1798ff542517..6d47f66f0e9c 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -23,6 +23,8 @@
 
 enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		FOR_ALL_ZONES(PGALLOC),
+		FOR_ALL_ZONES(PGSTALL),
+		FOR_ALL_ZONES(PGSCAN_SKIP),
 		PGFREE, PGACTIVATE, PGDEACTIVATE,
 		PGFAULT, PGMAJFAULT,
 		PGLAZYFREED,
@@ -37,7 +39,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 #endif
 		PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
 		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
-		PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+		PAGEOUTRUN, PGROTATED,
 		DROP_PAGECACHE, DROP_SLAB,
 #ifdef CONFIG_NUMA_BALANCING
 		NUMA_PTE_UPDATES,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bbd77fa4ec6a..a8b432ff0d14 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1394,6 +1394,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 	struct list_head *src = &lruvec->lists[lru];
 	unsigned long nr_taken = 0;
 	unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
+	unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
 	unsigned long scan, nr_pages;
 	LIST_HEAD(pages_skipped);
 
@@ -1408,6 +1409,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 
 		if (page_zonenum(page) > sc->reclaim_idx) {
 			list_move(&page->lru, &pages_skipped);
+			nr_skipped[page_zonenum(page)]++;
 			continue;
 		}
 
@@ -1436,8 +1438,17 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 	 * scanning would soon rescan the same pages to skip and put the
 	 * system at risk of premature OOM.
 	 */
-	if (!list_empty(&pages_skipped))
+	if (!list_empty(&pages_skipped)) {
+		int zid;
+
 		list_splice(&pages_skipped, src);
+		for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+			if (!nr_skipped[zid])
+				continue;
+
+			__count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
+		}
+	}
 	*nr_scanned = scan;
 	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan,
 				    nr_taken, mode, is_file_lru(lru));
@@ -2679,7 +2690,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 	delayacct_freepages_start();
 
 	if (global_reclaim(sc))
-		count_vm_event(ALLOCSTALL);
+		__count_zid_vm_events(PGSTALL, sc->reclaim_idx, 1);
 
 	do {
 		vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index ab7f78995c89..af070cf5e762 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -983,6 +983,8 @@ const char * const vmstat_text[] = {
 	"pswpout",
 
 	TEXTS_FOR_ZONES("pgalloc")
+	TEXTS_FOR_ZONES("pgstall")
+	TEXTS_FOR_ZONES("pgskip")
 
 	"pgfree",
 	"pgactivate",
@@ -1008,7 +1010,6 @@ const char * const vmstat_text[] = {
 	"kswapd_low_wmark_hit_quickly",
 	"kswapd_high_wmark_hit_quickly",
 	"pageoutrun",
-	"allocstall",
 
 	"pgrotated",
 
-- 
2.6.4

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  parent reply index

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-08  9:34 [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Mel Gorman
2016-07-08  9:34 ` [PATCH 01/34] mm, vmstat: add infrastructure for per-node vmstats Mel Gorman
2016-08-03 19:13   ` Reza Arbab
2016-07-08  9:34 ` [PATCH 02/34] mm, vmscan: move lru_lock to the node Mel Gorman
2016-07-12 11:06   ` Balbir Singh
2016-07-12 11:18     ` Mel Gorman
2016-07-13  5:50       ` Balbir Singh
2016-07-13  8:39         ` Vlastimil Babka
2016-07-08  9:34 ` [PATCH 03/34] mm, vmscan: move LRU lists to node Mel Gorman
2016-08-04 20:59   ` James Hogan
2016-08-05  8:41     ` Mel Gorman
2016-08-05 10:52       ` James Hogan
2016-08-05 11:55         ` Mel Gorman
2016-08-05 12:02           ` James Hogan
2016-07-08  9:34 ` [PATCH 04/34] mm, mmzone: clarify the usage of zone padding Mel Gorman
2016-07-12 13:49   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 05/34] mm, vmscan: begin reclaiming pages on a per-node basis Mel Gorman
2016-07-12 13:54   ` Johannes Weiner
2016-07-14  9:19   ` Vlastimil Babka
2016-07-08  9:34 ` [PATCH 06/34] mm, vmscan: have kswapd only scan based on the highest requested zone Mel Gorman
2016-07-12 14:05   ` Johannes Weiner
2016-07-13  8:37     ` Mel Gorman
2016-07-08  9:34 ` [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes Mel Gorman
2016-08-29  9:38   ` Srikar Dronamraju
2016-08-30 12:07     ` Mel Gorman
2016-08-30 14:25       ` Srikar Dronamraju
2016-08-30 15:00         ` Mel Gorman
2016-08-31  6:09           ` Srikar Dronamraju
2016-08-31  8:49             ` Mel Gorman
2016-08-31 11:09               ` Michal Hocko
2016-08-31 12:46                 ` Mel Gorman
2016-08-31 17:33               ` Srikar Dronamraju
2016-07-08  9:34 ` [PATCH 08/34] mm, vmscan: remove balance gap Mel Gorman
2016-07-12 14:06   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 09/34] mm, vmscan: simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-07-08  9:34 ` [PATCH 10/34] mm, vmscan: by default have direct reclaim only shrink once per node Mel Gorman
2016-07-08  9:34 ` [PATCH 11/34] mm, vmscan: remove duplicate logic clearing node congestion and dirty state Mel Gorman
2016-07-12 14:22   ` Johannes Weiner
2016-07-13  8:40     ` Mel Gorman
2016-07-14  9:45   ` Vlastimil Babka
2016-07-08  9:34 ` [PATCH 12/34] mm: vmscan: do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-07-12 14:29   ` Johannes Weiner
2016-07-13  8:47     ` Mel Gorman
2016-07-13 12:28       ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 13/34] mm, vmscan: make shrink_node decisions more node-centric Mel Gorman
2016-07-12 14:32   ` Johannes Weiner
2016-07-13  8:48     ` Mel Gorman
2016-07-08  9:34 ` [PATCH 14/34] mm, memcg: move memcg limit enforcement from zones to nodes Mel Gorman
2016-07-12 14:38   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 15/34] mm, workingset: make working set detection node-aware Mel Gorman
2016-07-08  9:34 ` [PATCH 16/34] mm, page_alloc: consider dirtyable memory in terms of nodes Mel Gorman
2016-07-08  9:34 ` [PATCH 17/34] mm: move page mapped accounting to the node Mel Gorman
2016-07-12 14:42   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 18/34] mm: rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-07-12 14:58   ` Johannes Weiner
2016-07-13  8:55     ` Mel Gorman
2016-07-13 13:04       ` Johannes Weiner
2016-07-13 13:37         ` Mel Gorman
2016-07-13 21:13           ` Andrew Morton
2016-07-15 10:46             ` Mel Gorman
2016-07-15 22:35               ` Andrew Morton
2016-07-18 13:34                 ` Johannes Weiner
2016-07-14  1:27           ` Minchan Kim
2016-07-08  9:34 ` [PATCH 19/34] mm: move most file-based accounting to the node Mel Gorman
2016-07-12 15:11   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 20/34] mm: move vmscan writes and file write " Mel Gorman
2016-07-12 15:15   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 21/34] mm, vmscan: only wakeup kswapd once per node for the requested classzone Mel Gorman
2016-07-12 17:18   ` Johannes Weiner
2016-07-08  9:34 ` [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest eligible zone Mel Gorman
2016-07-12 17:24   ` Johannes Weiner
2016-07-14 10:05   ` Vlastimil Babka
2016-07-08  9:34 ` [PATCH 23/34] mm: convert zone_reclaim to node_reclaim Mel Gorman
2016-07-12 17:28   ` Johannes Weiner
2016-07-08  9:35 ` [PATCH 24/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node Mel Gorman
2016-07-12 17:31   ` Johannes Weiner
2016-07-14 10:09   ` Vlastimil Babka
2016-07-08  9:35 ` [PATCH 25/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready Mel Gorman
2016-07-12 18:01   ` Johannes Weiner
2016-07-14 12:12   ` Vlastimil Babka
2016-07-08  9:35 ` [PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep Mel Gorman
2016-07-12 18:06   ` Johannes Weiner
2016-07-14 12:48   ` Vlastimil Babka
2016-07-08  9:35 ` [PATCH 27/34] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit Mel Gorman
2016-07-12 18:10   ` Johannes Weiner
2016-07-14 12:54   ` Vlastimil Babka
2016-07-08  9:35 ` [PATCH 28/34] mm, vmscan: add classzone information to tracepoints Mel Gorman
2016-07-12 18:13   ` Johannes Weiner
2016-07-08  9:35 ` [PATCH 29/34] mm, page_alloc: remove fair zone allocation policy Mel Gorman
2016-07-12 18:18   ` Johannes Weiner
2016-07-08  9:35 ` [PATCH 30/34] mm: page_alloc: cache the last node whose dirty limit is reached Mel Gorman
2016-07-12 18:43   ` Johannes Weiner
2016-07-08  9:35 ` [PATCH 31/34] mm: vmstat: replace __count_zone_vm_events with a zone id equivalent Mel Gorman
2016-07-12 19:10   ` Johannes Weiner
2016-07-08  9:35 ` Mel Gorman [this message]
2016-07-12 19:06   ` [PATCH 32/34] mm: vmstat: account per-zone stalls and pages skipped during reclaim Johannes Weiner
2016-07-08  9:35 ` [PATCH 33/34] mm, vmstat: print node-based stats in zoneinfo file Mel Gorman
2016-07-12 19:18   ` Johannes Weiner
2016-07-14 12:56   ` Vlastimil Babka
2016-07-08  9:35 ` [PATCH 34/34] mm, vmstat: remove zone and node double accounting by approximating retries Mel Gorman
2016-07-14 13:40   ` Vlastimil Babka
2016-07-15  7:48     ` Mel Gorman
2016-07-15 12:20       ` Vlastimil Babka
2016-08-19 13:12 ` [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Andrea Arcangeli
2016-08-19 13:23   ` Vlastimil Babka
2016-08-19 13:55     ` Andrea Arcangeli
2016-08-19 14:53   ` Mel Gorman
2016-08-19 15:32     ` Andrea Arcangeli
2016-08-19 15:55       ` Mel Gorman

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